It is known for the tubular casing required for the production of sausages or similar portion packs to be continuously produced in situ by longitudinal seam welding or sealing of a film strip which is bent into the tubular form. In the process of the general kind set forth which is known from EP 0 908 103 A1, the film strip is pulled through the welding or sealing station by advance drive means over a shaping shoulder. The shaping shoulder concentrically surrounds the filling tube which guides the filling material, and both the welding or sealing device and also the advance drive means operate against the filling tube. The tubular film which is formed in that way is conveyed by the advance drive means into a buffer station in which it is folded together in a harmonica-like configuration. On the other side of the buffer station it is drawn out of same upon filling of a portion into the tubular film which is closed at one end, through a sausage case brake device arranged at the mouth opening of the filling tube, until the filling operation in question is concluded and the portion can be closed.
That operating procedure is complicated and expensive in terms of apparatus and control technology because the operation of closing the tubular film and the filling operation have to be monitored and controlled independently of each other. For, due to a variation in the filling speed, the size of the portions and so forth, the requirement for tubular film in a unit of time fluctuates within relatively wide limits; however, adaptation of the continuous tubular film production speed is not possible or is very complicated and expensive, for a number of reasons.